If you could control the brain of a rat with your thoughts, what would you tell it to do? Perhaps you'd to tell it to go away. Or, if you were feeling mischievous, maybe you'd encourage it to creep into a sibling's bed or scurry across the floor of a crowded room. For proof-of-concept, scientists kept it simple. They asked human volunteers to move a rat's tail simply by thinking about it—a feat they actually accomplished, with the aid of brain-to-brain interface technologies that transmitted electrical signals from the human to the rat brain. The experiment, which was reported recently in the journal PLoS ONE, was based on computer-to-brain interfacing with electroencephalography (EEG) in humans and focused brain ultrasound in rats. The humans conveyed their intention of moving the rats' tails by watching a computer display of a flickering strobe light. EEG captured the electrical activity associated with their thought processes while watching the strobe. When EEG signals became synchronized with signals from the visual stimuli, a spike in signal amplitude occurred, which was detected by the computer and subsequently relayed to the ultrasound electronics, triggering a burst of focused ultrasound to the rat brain. The burst, focused onto a specific area of the motor cortex in the brain of the anesthetized rat, ultimately produced a flick of the tail. The ability to control the thoughts of others is of special interest in the study of cognitive processes, and it could find applications in neurotherapy or even as a novel mode of communication in "brain-to-brain coupling." The practicality of these applications, however, remains to be explored. In the meantime, in highlighting the fine line between fiction and reality, the new study gives us plenty to think about. Indeed, Ratatouille could become more human-like than he ever imagined. In a text, the main point an author is trying to convey is called the text's
  A.central idea
  B.formal diction
  C.key information
  D.topic sentence